1. Field of the Invention
The present invention relates to a pressure controlled sprayer device, and more particularly, to a miniature atomizer of the manual type for atomizing to a state of fine spray cosmetic, perfume and similar products.
2. Description of the Prior Art
Pressure controlled sprayer devices including miniature atomizers of the manual type are known in the prior art. An example of such an atomizer is shown in U.S. Pat. No. 4,017,031, Kishi et al wherein vertically disposed axially aligned first and second cylinders of different diameters are formed in a communicating passage extending from a container holding the liquid product to be atomized to a nozzle outlet in the atomizer head, the lower cylinder being that having the smaller diameter. A tubular member having a connection to the atomizer head and extending between the cylinders includes a tubular piston on each end to provide a sliding seal with the associated cylinder. An inlet check valve is provided at the lower end of the smaller cylinder for controlling withdrawal of liquid from the container and a piston valve in the upper end of the larger cylinder controls the flow of liquid to the nozzle outlet. The inlet check valve and the piston valve thus form a pressure chamber between them. Actuation of the atomizer to force the tubular member down into the smaller cylinder, the return action being by way of a piston return coil spring member, boosts the pressure in the chamber to a predetermined level at which the piston valve opens to allow liquid to flow through the bore of the tubular member and out of the nozzle outlet. The liquid discharged is mixed with air at the nozzle outlet to form a fine mist.
In the action of such miniature atomizers it is imperative for the pressure in the chamber at which such discharge occurs to be independent of the finger force applied by the operator in depressing the atomizer head to the end that the discharge is a uniform mist, without dribble, particularly at the beginning and the end of each spray cycle. Such action is termed by the industry as non-throttling action, and is the desired mode of operation.
While the prior art miniature atomizers, as described, are considered non-throttling, they depend for uniformity of spray pattern upon a "specific combination" of function, that is, a relation of cylinder diameter ratios in combination with a single spring force in line with the two cylinders which has a direct bearing on the force used to actuate the atomizer. This is to say, the predetermined pressure at which the piston valve opens depends upon the force of the piston return spring which together with the internal pressure built up in the smaller cylinder determines the magnitude of finger force needed to depress the actuator for the tubular member. The magnitude of the force applied to the actuator accordingly is a variable that can alter the spray pattern and other such variables are nozzle outlet or orifice size and orifice land thickness. The prior art apparatus thus allows three variables to alter the spray pattern and break up for particle sizes.
Other disadvantages of the prior art miniature atomizers stem from the structural arrangements and the number of component parts required, some of which are very small and consequently difficult to handle, thereby making assembly difficult, and from the component parts configuration as affecting material cost, assembly and molding costs. By way of example, as the size of the atomizers have been scaled down, the return coil spring has become smaller and smaller to the extent that it is troublesome to handle both in storage and assembly, and moreover, its location in the smaller cylinder in contact with the product to be sprayed requires the use of special spring wire material that is inert to such product and which adds to the cost of materials required.